Diaphragm pump with annular pumping chamber



Dec. 13, 1966 T 3,291,064

DIAPHRAGM PUMP WITH ANNULAR PUMPING CHAMBER Filed Jan. 25, 1963 INVENTOR.

TTORNEY United States Patent 3,291,064 DIAPHRAGM PUMP WITH ANNULAR PUMPING CHAMBER Michael R. Foster, Flint, MiclL, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Jan. 25, 1963, Ser. No. 253,862 1 Claim. (Cl. 103-150) This invention relates to pumps and more particularly to diaphragm pumps suitable for handling fuel for internal combustion engines.

A very satisfactory diaphragm pump is disclosed in the United States Patent No. 3,008,427, granted November 14, 1961, in the names of M. R. Foster and R. G. Taylor. This patented pump requires two diaphragmsone for pump-ing and one for sealing. The sealing diaphragm is effective in performing its function but it decreases volumetric efficiency, increases the cost of manufacture, and necessitates an added pump body casting.

An object of the present invention is to provide an improved diaphragm pump of simplified construction permitting a long pump stroke, low cost and increased volumetric efficiency.

A feature of the present invention is a diaphragm pump in which inner and outer portions of a pumping diaphragm are held stationary to gain a sealing effect and another or annular portion arranged to be actuated to gain a pumping effect.

"These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claim.

The single figure shows a sectional view of the invention.

In the drawing, a cast pump body is depicted at 10. It is provided with a depending hub 12 adapted to be inserted and held in a port of .an engine block or crankcase not herein disclosed. A camshaft 14 is depicted in position to cause engagement of a cam surface 16 with the end of a reciprocable and guided member 18. The other end of this member is in contact with the lower end of an operating rod 20. The latter extends upwardly through the hub 12 of the pump and is placed in sliding relation within a bore 22 of a retainer 24. The latter has a mushroom shaped head 26 and is tightly held within a bore 27 of the body by means of a nut 28 engaging the retainer 26 .by means of threads 30. The underside 29 of head 26 has a curved configuration conforming to the curved opening 31 of bore 27 to provide corresponding sealing surfaces. The not 28 bears against an inside shoulder 34 of the body 10 and the retainer head 26 serves to clamp or fix an inner portion 35 of a pumping diaphragm 36 in sealed relation with an annular upstanding portion 3 8 of the pump body. An inlet 40 and an inlet chamber 42 are shown in the body 10 as being controlled by a pressure actuated and conventional one-way valve 44. This valve is adapted to admit fuel to an annular pumping chamber 46 defined between the underside of the diaphragm 36 and the body 10. The latter is also recessed to accommodate an outlet valve 48 leading one way and from the pumping chamber 46 to an outlet chamber 50 and an outlet 52.

The upper end of the operating rod has two integral 3,291,064 Patented Dec. 13, 1966 'ice portions 54 and 56 between which is tightly held an inverted cnplike portion of a diaphragm backing plate 58. The backing plate is so formed as to enclose the head 26 of the retainer and movably support an annular portion 60 of the diaphragm 36. The latter is firmly clamped to the plate 58 by means of an annular ring 64. The latter is held to the plate 58 by means of upset rivetlike projections 66. The outer margin 68 of the plate 58 is so foamed as to extend downwardly between the ring 64 and the wall surface 70 inside the pump body 10 and then curve upwardly for smooth engagement with the diaphragm. Because of the contour of the wall surface 70 and the margin 68 of the plate 58, the pumping diaphragm forms a bight extending into the pumping chamber 46. It will be noted that the pumping diaphragm 36 is so assembled with respect to the ring 64 and the annular portion 38 of the pump body that a second and inner bigh-t 74 also extends downwardly further to restrict the volume of the pumping chamber. The bights of the pumping diaphragm are most pronounced when the actuating rod 20 has moved downwardly a maximum extent thereby evacuating the pumping chamber 46 a maximum extent as will be understood. At the completion of a suction or upward stroke, the bights will practically disappear as the requisite flexure of the diaphragm occurs.

The outer margin or periphery of the diaphragm 36 is tightly held to the body 10' by means of a sheet metal cover member which is crimped or spun over as at 82 around .an annular shoulder portion 84 of the pump body. This cover member 80 is apertured as at 86 to prevent entrapment of air and a coil spring 88 is located in the cover member 80 and is placed in compression between the latter and the backing plate 58. Venting of the space between the plate 58 and the head 26 is not necessary as the bore 22 extends down to the exterior of the pump.

In the operation of the pump, the rotation of the cam 116 will cause consecutive upward movements of the operating rod 20 and consequent suction strokes of the annular portion 60 of the diaphragm 36. The spring 88 serves to effect consecutive downward or pumping strokes.

It will be noted that only one diaphragm is necessary and that the inner and outer seals utilizing the diaphragm 36 to determine the pumping chamber 46 presents a structure of simplicity and ruggedness.

I claim:

A pump comprising a body and an annular diaphragm cooperating to define an annular pumping chamber, an inlet and outlet to said chamber, pressure actuated valves controlling said inlet and outlet, a pumping spring, an apertured cover member clamping the outer periphery of said diaphragm to said body and forming an open enclosure for said pumping spring, said body including an elongated passage with an upper curved opening and a lower passage opening, a retainer with an axial bore extending through said passage and having an enlarged head portion on one end and an external threaded portion on the other end, said retainer head portion having a curved surface conforming to the configuration of said curved passage opening to provide complementary surfaces for sealing the inner periphery of said diaphragm within said body passage and between said curved surfaces, securing means being mounted on said retainer threaded portion engaging an outer portion of said body adjacent said lower passage opening to seal the inner periphery of said diaphragm between said retainer and said body, a plate fixed to said diaphragm between said outer and inner peripheries and extending across the axis of said bore and clear of said retainer, a rod extending through said bore and fixed to said plate for actuating said diaphragm during suction strokes, said pumping spring acting between said cover member and said plate to effect pumping strokes, and said diaphragm constituting the sole resilient seal between said body and rod.

References Cited by the Examiner UNITED STATES PATENTS Rand 103--149 Foster et a1. 103-150 Gemeinhardt 103149 X Shope 103-450 Johnson 103150 

